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A commonly used test of the balance system – which uses water of varying temperatures to indirectly stimulate the brain – may bring a temporary awareness of illness to people with schizophrenia who feel they are not ill.

This pilot proof-of-concept study was led by Dr. Philip Gerretsen, who received a New Investigator Award to present results at the American Society of Clinical Psychopharmacology (ASCP) 2014 Annual Meeting in June.

Many people with schizophrenia, dementia and strokes may not have full insight into their illness. This condition, known as anosognosia, can affect whether a person follows their treatment, and their health can suffer as a result, says Dr. Gerretsen, a geriatric psychiatrist and post-doctoral clinical fellow at CAMH.

The test, caloric vestibular stimulation (CVS), is commonly used by ear, nose, and throat specialists and audiologists to test patients' balance. CVS involves irrigating the ear canal with water. Depending on the temperature of the water and which ear is irrigated, the procedure can stimulate different areas of the brain, which has been seen in brain imaging studies.

Dr. Gerretsen devised the idea of using this test for schizophrenia, building on research on patients with stroke damage in the right hemispheres of their brains. These individuals show a lack of awareness that they are paralyzed.

"Research has shown that cold water in the left ear of stroke patients with right hemisphere damage can reverse the lack of awareness of paralysis, so that they gain awareness from 30 minutes to as much as two hours after the test that they have neurological deficits," he says.

Dr. Gerretsen and co-investigator Dr. David D. Pothier, from the University of Toronto, tested CVS in 13 patients with schizophrenia spectrum disorder, who had moderate to severe insight impairment based on a measure from the Positive and Negative Syndrome Scale (PANSS).The study participants were given, in a random order, one of three tests: cold CVS in their left ear with a water temperature of 4° C, cold CVS in their right ear, and sham CVS, in which the water was at body temperature. Patients' insight into their illness was assessed at five, 30, and 60 minutes after CVS, using the VAGUS Insight into Psychosis Scale. This scale was designed to capture subtle changes in insight over a short period of time.

CVS with cold water in the left ear significantly increased patients' insight and awareness of their illness at 30 minutes after the test, compared with the sham and right ear, cold water treatments. However, by 60 minutes, this insight had diminished.

"We plan to do further research to find ways to make the transient period of awareness last longer," says Dr. Gerretsen. One approach would be to apply CVS for five consecutive days to see if effects last longer.

Dr. Gerretsen and his supervisors, Scientists Drs. Ariel Graff and Bruce G. Pollock, have also begun another proof-of-concept study of a non-invasive brain stimulation approach, called transcranial direct current stimulation (tDCS), to determine its effect on illness awareness. The current study was funded by the Ontario Mental Health Foundation.